To cite package rtop in publications use:

Skoien J, G. Bloschl, G. Laaha, E. Pebesma, J. Parajka, A. Viglione (2014). “Rtop: An R package for interpolation of data with a variable spatial support, with an example from river networks.” Computers & Geosciences.

Corresponding BibTeX entry:

  @Article{,
    title = {Rtop: An R package for interpolation of data with a
      variable spatial support, with an example from river networks},
    author = {J. O. Skoien and {G. Bloschl} and {G. Laaha} and {E.
      Pebesma} and {J. Parajka} and {A. Viglione}},
    journal = {Computers & Geosciences},
    year = {2014},
  }